We intend to further examine changes in the structure of the nitrogenase protein in various enzymatic states. The MoFeS M-center is the proposed active site of nitrogen fixation while the FeS P-cluster provides electrons necessary for the fixation process. We also want to reproduce preliminary structural EXAFS data on one electron reduced nitrogenase protein to compare with resting protein. Finally, we want to do studies on CO-inhibited nitrogenase, which is proposed to bind to the M-center, to gain insight on changes due to binding at the M-center.